Using a DNS name is preferred to using an IP address in VoIP Detective.  This is primarily because licensing is tied to site URL, and using a DNS name guarantees that it will be unique.  If you use a DNS name for the "Site URL" of VoIP Detective, but fail to set the DNS name in the CLI, VoIP Detective will end up not responding to calls to itself.  This makes setting the DNS name very important.

Setting the hostname on your VoIP Detective installation

Before setting the hostname, you'll likely need to assign a static IP address.  Instructions for that can be found here.

The hostname for VoIP Detective is set through the CLI.  You can use SSH, or the VMware console, and login.  The default credentials can be found here.

Choose the option to configure network settings, and you are presented with this menu

Just enter the fully qualified domain name that your VoIP Detective installation will use and hit OK.

Reboot the virtual machine to apply any changes.

Be sure that the proper records have been created in your DNS server for this new DNS name